Kyung-Hoon Hyun and Patrick Hogan, Naval Research Lab.
The topographic effect and two non-dimensional parameters have been known to control the evolution of an eddy: the ratio delta of the thickness of the eddy to the total depth, and the beta-effect number alpha=beta*L/f (f and beta are the Coriolis parameter and its meridional gradient respectively, L is the radius of the eddy). The role of these parameters in eddy propagation has been examined using the HYCOM model.
The evolutions of various eddies with different initial radii and depths were simulated for one year. The eddy was initially located deep offshore and near the slope to see the topographic effect. Simulations show the following significant results:
1) The eddy splits into two or three small eddies but there is a main
eddy
that represents the eddy evolution. The main eddy hardly crosses the
shelf
break.
2) Deeper and bigger eddies propagate faster, which indicates that an
eddy
propagates faster as alpha and delta increase.
3) Meridional drift increases as eddy size increases, which indicates
fast meridional evolution as delta increases.
4) The eddy initially located near the slope splits into two eddies:
one
propagating meridionally along the slope and the other trapped over the
slope.